In recent years, displays of image display devices including television receivers are shifting from conventional cathode-ray tube displays to thin-screen displays including liquid crystal panels and plasma display panels. With the thin-screen displays, thin image display devices can be provided. A liquid crystal display device requires a backlight unit as a separate lighting device because a liquid crystal panel used therein is not a light-emitting component.
A technology to provide thin and large-screen liquid crystal display devices is disclosed in Patent Document 1. A backlight unit disclosed therein includes LEDs and light guide plates. Each LED has a light-emitting surface through which light is emitted in the direction substantially parallel to a display surface of a liquid crystal panel. Each light guide plate has a light entrance surface in a side area (a side-edge area) and a light exit surface on a front surface. The light entrance surface faces the LED. Light emitted from the LED enters the light guide plate through the light entrance surface and exit from the light exit surface toward the display surface of the display panel. The light guide plates and the LEDs are arranged in lines that are parallel to each other. Each line contains a plurality of the light guide plates and the LEDs and extends in a direction parallel to an arrangement direction in which each light guide plates and the corresponding LED are arranged. The adjacent light guide plates overlap each other.    Patent Document 1: Japanese Published Patent Application No. 2001-93321